PHP development verification code mixed letter and number verification code

Mixed letters and numbers verification code

Make the verification code content display a mixture of letters and numbers

<?php
 $image = imagecreatetruecolor(100,30);
 $bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF
 imagefill($image,0,0,$bgcolor);
 for ($i=0;$i<4;$i++){
     $fontsize = 6;
     $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
     $data='abcdefghijklmnopqrstuvwxyz1234567890';
     $fontcontent=substr($data,rand(0,strlen($data)),1);
     $x = ($i * 100/4)+rand(5,10);
     $y = rand(5,10);
     imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
 }
 for($i=0;$i<200;$i++){
     $pointcolor = imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200));
     imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor);
 }
 for($i=0;$i<8;$i++){
     $linecolor = imagecolorallocate($image,rand(60,220),rand(60,220),rand(60,220));
     imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor);
 }
 header('content-type: image/png');
 imagepng($image);
 //销毁
 imagedestroy($image);
 ?>

Verification code of letters and numbers The difference is not big, you just need to change the generated numbers into letters and numbers.

for ($i=0;$i<4;$i++){
     $fontsize = 6;
     $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
     $data='abcdefghijklmnopqrstuvwxyz1234567890';
     $fontcontent=substr($data,rand(0,strlen($data)),1);
     $x = ($i * 100/4)+rand(5,10);
     $y = rand(5,10);
     imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
 }

The difference is $data='abcdefghijklmnopqrstuvwxyz1234567890';Define a dictionary

Define the $fontcontent function and intercept the contents in the dictionary The number is displayed immediately.